The places in your city that you really like, but rarely go to unless you have out-of-town company. This is in contrast with tourist traps--places that you never go to unless you have out-of-town company, and even then, try to talk them out of. There's an additional step up, which is place a local would take you, that you otherwise wouldn't ever hear about.

For San Francisco

place a local would take you

the ruins of sutro baths
little-known, but great restaraunts

local pick

exploratorium
well-known, and deservedly so restaraunts

tourist trap

fisherman's wharf
trendy but lousy restaraunts